Owen A M, Roberts A C, Hodges J R, Summers B A, Polkey C E, Robbins T W
Department of Experimental Psychology, University of Cambridge, UK.
Brain. 1993 Oct;116 ( Pt 5):1159-75. doi: 10.1093/brain/116.5.1159.
Tests which assess the ability to shift cognitive set modelled after the Wisconsin Card Sorting Test are particularly sensitive to impairments in patients with Parkinson's disease as well as in patients with frontal lobe damage. However, the underlying mechanisms responsible for the similar deficits observed in the two patient groups are not well understood and may not be identical. For example, an apparent deficit in set-shifting ability may reflect either an impairment in the ability to shift from a perceptual dimension which has previously commanded attention (i.e. 'perseveration'), or in the ability to shift to an alternative perceptual dimension which has previously been irrelevant (i.e. 'learned irrelevance'). In this study, the performance of both medicated and non-medicated patients with Parkinson's disease were compared with a group of neurosurgical patients with localized excisions of the frontal lobes on a novel task designed to assess the relative contribution of 'perseveration' and 'learned irrelevance' to impaired set-shifting ability. Patients with frontal lobe damage were worse than controls in their ability to shift attention from a previously relevant stimulus dimension. Medicated patients with Parkinson's disease were worse at shifting to a previously irrelevant dimension. In contrast to both groups, nonmedicated patients with Parkinson's disease were impaired in both conditions. These results suggest that the gross set-shifting deficits reported in both frontal lobe patients and patients with Parkinson's disease may involve fundamentally different, though related, cognitive processes, and that these may be differentially affected by medication. Specifically, L-dopa therapy may protect Parkinson's disease patients from preservation of attention to a formerly relevant stimulus dimension.
模仿威斯康星卡片分类测试设计的、用于评估认知转换能力的测试，对帕金森病患者以及额叶损伤患者的功能障碍特别敏感。然而，导致两组患者出现类似缺陷的潜在机制尚未完全明确，可能并不相同。例如，明显的转换能力缺陷可能反映出从先前吸引注意力的感知维度进行转换的能力受损（即“持续性”），或者是转换到先前无关的另一个感知维度的能力受损（即“习得性无关”）。在本研究中，将帕金森病的服药患者和未服药患者的表现，与一组进行了额叶局部切除的神经外科患者在一项新任务中的表现进行了比较，该任务旨在评估“持续性”和“习得性无关”对转换能力受损的相对影响。额叶损伤患者将注意力从先前相关的刺激维度上转移的能力比对照组差。帕金森病的服药患者在转移到先前无关维度方面表现更差。与这两组患者不同的是，帕金森病的未服药患者在两种情况下均受损。这些结果表明，额叶患者和帕金森病患者中报告的总体转换缺陷可能涉及根本不同但相关的认知过程，并且这些过程可能受到药物的不同影响。具体而言，左旋多巴治疗可能使帕金森病患者避免持续关注先前相关的刺激维度。
